DEBT - Interest Costs Recognized on 2026 Notes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Debt Instrument [Line Items]
Total interest expense recognized	$ 2,329	$ 2,362	$ 6,895	$ 6,662
Convertible Debt | 2026 Notes
Debt Instrument [Line Items]
Contractual interest expense	289	454	880	1,053
Amortization of debt discount and issuance costs	2,040	1,908	6,015	5,609
Total interest expense recognized	$ 2,329	$ 2,362	$ 6,895	$ 6,662